Additive for reclamation of asphalt, reclaimed asphalt pavement material containing same, modified asphalt, and asphalt pavement material containing same

ABSTRACT

An additive for reclaiming asphalt of the present invention, which is obtained by adding straight asphalt to a mixture of a waste animal or vegetable oil and a waste mineral oil having a kinematic viscosity at 60° C. of 10 mm 2 /s to 40 mm 2 /s, mixing the materials, and heating the resultant mixture to remove an aromatic component. The additive for reclaiming asphalt can restore the physical properties of a deteriorated asphalt component to the same or greater extent than that of a conventional additive for reclaiming asphalt, and the additive has low content of components that may affect the environment or humans, and high fluidity at room temperature, and is available at an extremely low cost.

TECHNICAL FIELD

The present invention relates to an additive for reclaiming asphalt, areclaimed asphalt pavement material that contains same, a modifiedasphalt, and an asphalt pavement material that contains same.

BACKGROUND ART

The total amount of production of asphalt mixtures is decreasing eachyear after reaching a peak in 1989 (see Non Patent Document 1). This isbecause the length of roads paved with asphalt in Japan has alreadyreached 1,190,000 km and hence the number of roads to be newlyconstructed is reducing. Meanwhile, the reclamation rate of asphaltpavement waste, which was 7.6% in 1989, continues to increase abruptly,reaching 73.1% in 2008. This trend is expected to become stronger andstronger in the future as well.

Two methods each involving restoring the physical properties of anasphalt component that has deteriorated over time with an additive forreclaiming asphalt have been known for the reclamation of asphaltpavement waste (see Non Patent Document 2). One of the methods is aroad-surface recycling method (remix system and repave system) but thisis seldom adopted in Japan. The other is a plant recycling pavementmethod (plant mix system) which has gone mainstream in Japan. Severalkinds of products (each using, for example, a semi-refined oil at thetime of petroleum refining as a main raw material) have beencommercially available as additives for reclaiming asphalt that can beused in the plant recycling pavement method. However, the products arenot only expensive, but the products have high viscosities (are greasy)at room temperature and hence need to be heated to about 70° C. to 80°C. at all times. Accordingly, it is inconvenient to handle the productsand heat source costs are required. In addition, concerns are raisedabout the effect of the products on the environment and humans becausethe products each contain large amounts of aromatic components.

In view of the foregoing, for example, an additive for reclaimingasphalt obtained by blending a mineral oil having a kinematic viscosityat 60° C. of 100 to 1,000 mm²/s, and a fat, the additive having akinematic viscosity at 60° C. of 20 to 300 mm²/s and a flash point of220° C. or more (see Patent Document 1), and an additive for reclaimingasphalt obtained by blending a mineral oil having a kinematic viscosityat 40° C. of 300 to 900 mm²/s and a polycyclic aromatic content of lessthan 3 wt %, and a fat, the additive having a kinematic viscosity at 40°C. of 40 to 400 mm²/s, a polycyclic aromatic content of less than 3 wt %and a flash point of 220° C. or more (see Patent Document 2), have beenproposed. However, the high-viscosity mineral oils used in PatentDocuments 1 and 2 are expensive because the oils are generally refinedto a high degree, resulting in the prices of the products also becomehigh.

In addition, modified asphalt obtained by adding plastic, rubber, or thelike to straight asphalt to improve the properties of the asphalt hasbeen known. For example, Patent Document 3 proposes a modified asphaltformed of asphalt, a waste plastic such as a waste polystyrene, and awaste oil containing an engine oil as a main component. An upper limitfor the content of the waste plastic in the modified asphalt disclosedin Patent Document 3 is set to 40 wt %. This is because when the wasteplastic is added at a content in excess of 40 wt %, curing startsimmediately after the mixing of the materials and hence the resultantproduct cannot be used as a modified asphalt (see Comparative Example ofPatent Document 3). In the industry, however, a modified asphalt blendedwith an additionally large amount of plastic, rubber, or the like is indemand in expectation of further improvements in the properties ofasphalt.

PRIOR ART Patent Document

-   [Patent Document 1] Japanese Patent Laid-Open No. 2005-154465-   [Patent Document 2] Japanese Patent Laid-Open No. 2005-154464-   [Patent Document 3] Japanese Patent Laid-Open No. 2006-143954

Non Patent Document

-   [Non Patent Document 1] “The Annual Statistical Report of Asphalt    Mixtures 2008,” Japan Asphalt Mixture Association eds.-   [Non Patent Document 2] “Manual for Pavement Recycling,” Japan Road    Association eds., February 2004, p. 12, p. 207

SUMMARY OF INVENTION Technical Problem

Therefore, the present invention has been made to solve theabove-mentioned problems, and an object of the present invention is toprovide an additive for reclaiming asphalt which restores the physicalproperties of a deteriorated asphalt component to the same extent asthat of a conventional additive for reclaiming asphalt, but has lowcontent of components that may affect the environment or humans, hashigh fluidity at room temperature, and is available at an extremely lowcost.

In addition, the present invention has been made to solve theabove-mentioned problems, and an object of the present invention is toprovide a modified asphalt which can be blended with a large amount of aresin component and which shows improved properties of asphalt.

Solution to Problem

An additive for reclaiming asphalt according to the present invention isobtained by adding straight asphalt to a mixture of a waste animal orvegetable oil and a waste mineral oil having a kinematic viscosity at60° C. of 10 to 40 mm²/s, mixing the materials, and heating theresultant mixture to remove an aromatic component.

In addition, the present invention is a reclaimed asphalt pavementmaterial obtained by adding the above-mentioned additive for reclaimingasphalt to an asphalt pavement waste or a mixture of a fresh aggregateand an asphalt pavement waste.

In addition, a modified asphalt according to the present invention isobtained by adding, to molten straight asphalt, a xerogel-like amorphousresin, which is obtained by dissolving an amorphous resin with anorganic solvent capable of dissolving the amorphous resin to provide agel- or dough-like amorphous resin in a saturated state, immersing theresin in alcohol to remove the organic solvent, and drying theremainder, together with a waste animal or vegetable oil, and mixing thematerials.

In addition, a modified asphalt according to the present invention isobtained by adding, to molten straight asphalt, a product, which isobtained by dissolving an amorphous resin with an organic solventcapable of dissolving the amorphous resin to provide a gel- ordough-like amorphous resin in a saturated state, and heating the resinto melt the resin, together with a waste animal or vegetable oil, andmixing the materials, wherein the content of the gel- or dough-likeamorphous resin in the modified asphalt is 70 wt % to 90 wt %.

Further, the present invention is an asphalt pavement material where theabove-mentioned modified asphalt is added to a fresh aggregate, anasphalt pavement waste, or a mixture of a fresh aggregate and an asphaltpavement waste.

Advantageous Effects of the Invention

According to the present invention, it is possible to provide anadditive for reclaiming asphalt which restores the physical propertiesof a deteriorated asphalt component to the same extent as that of aconventional additive for reclaiming asphalt, has low content ofcomponents that may affect the environment or humans, has high fluidityat room temperature, and is available at an extremely low cost.

Further, according to the present invention, it is possible to provide amodified asphalt which can be blended with a large amount of a resincomponent and which shows improved properties of asphalt.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph showing a surface state after a wheel trackingtest for the reclaimed asphalt pavement material obtained in Example 15.

FIG. 2 is a photograph showing a surface state after a wheel trackingtest for the asphalt pavement material obtained in Comparative Example8.

FIG. 3 is a photograph showing a surface state after a wheel trackingtest for the asphalt pavement material obtained in Comparative Example9.

FIG. 4 is a photograph showing a fracture cross-section of the reclaimedasphalt pavement material obtained in Example 15.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the present invention will be described in detail.

First, an additive for reclaiming asphalt of the present invention isdescribed.

In industry, compensating for aromatic components in asphalt lost by itsdeterioration has heretofore been considered most important in restoringthe physical properties of the asphalt, and hence most of theconventional additives for reclaiming asphalt have each contained alarge amount of an aromatic component. However, the inventor of thepresent invention has judged from previous experiences that the aromaticcomponent is not useful in restoring the physical properties of asphaltbecause most of the component evaporates at the time of heating andmixing. In view of the foregoing, the inventor of the present invention,after conducting intensive studies and development for restoring thephysical properties of asphalt through the control of the softening anddispersion of the asphalt, has found that that a product obtained bydissolving straight asphalt in a mixture of a waste animal or vegetableoil and a waste mineral oil, and removing aromatic components from thesolution is useful, to complete the present invention.

That is, an additive for reclaiming asphalt of the present invention isobtained by adding straight asphalt to a mixture of a waste animal orvegetable oil and a waste mineral oil having a kinematic viscosity at60° C. of 10 mm²/s to 40 mm²/s, mixing the materials, and heating theresultant mixture to remove aromatic components. A temperature for theheating may be a temperature at which the aromatic components mainlyincorporated into the waste mineral oil and the straight asphalt can beremoved, and is preferably 230° C. to 250° C.

A mixing ratio of the waste animal or vegetable oil to the waste mineraloil having a kinematic viscosity at 60° C. of 10 mm²/s to 40 mm²/s ispreferably 1:9 to 99.1:0.1, more preferably 1:9 to 9:1, most preferably5:5 to 9:1 on a weight basis from the viewpoint of balance between thesoftening of the straight asphalt from the waste mineral oil and thedispersibility of the straight asphalt from the waste animal orvegetable oil. The mixing ratio of the waste animal or vegetable oil isdesirably increased to raise the flash point of the additive in order tofurther improve safety at the time of its production. In addition, theaddition amount of the straight asphalt is preferably such an amountthat the additive for reclaiming asphalt has a kinematic viscosity at60° C. of 80 mm²/s to 200 mm²/s, and is typically 3 wt % to 30 wt % withrespect to the additive for reclaiming asphalt, though the preferredamount varies depending on the degree of penetration of the straightasphalt. Straight asphalts having a penetration degree of 20 to 80 arepreferably used. Of those, straight asphalt having a penetration degreeof 20 to 40 is desirable because the kinematic viscosity can be adjustedto a desired level with a small addition amount.

A waste vegetable oil, or waste animal oil discarded from ordinaryhouseholds, eateries, or the like can be used as the waste animal orvegetable oil in the present invention, and such waste animal orvegetable oil typically has a kinematic viscosity at 60° C. of 60 mm²/sto 150 mm²/s.

The waste mineral oil in the present invention may be any waste mineraloils having a kinematic viscosity at 60° C. of 10 mm²/s to 40 mm²/s, andwaste lubricating oil, waste engine oil, or the like discarded from gasstations or the like can be used. In addition, a waste animal orvegetable oil and a waste mineral oil treated in advance with afiltering apparatus such as a strainer in order to remove foreign matterin the waste animal or vegetable oil and the waste mineral oil arepreferably used. It should be noted that the kinematic viscosity is avalue determined according to JIS K2283.

The additive for reclaiming asphalt of the present invention has anexcellent ability to restore the physical properties of a deterioratedasphalt component, has low content of aromatic components that mayaffect the environment or humans, and has such a high fluidity at roomtemperature that the additive can be directly used as an additive in aplant mix system without being heated. In addition, the additive isavailable at an extremely low cost because the additive utilizes wasteproducts. Further, the additive for reclaiming asphalt of the presentinvention has an advantage that the physical properties of thedeteriorated asphalt component can be restored with a smaller additionamount than that of a conventional additive for reclaiming asphalt.

A reclaimed asphalt pavement material of the present invention isobtained by adding the additive for reclaiming asphalt to an asphaltpavement waste or a mixture of a fresh aggregate and the asphaltpavement waste, and melting and mixing the materials under temperaturesof 150° C. to 180° C. In the present invention, the additive forreclaiming asphalt and a modified asphalt that is described later may beused in combination. When the modified asphalt is used in combination,the melting and mixing can be performed under temperatures of 150° C. to170° C.

Here, examples of the asphalt pavement waste include products (recycledaggregates) obtained by pulverizing asphalt pavement waste generatedduring various types of construction (such as road pavement constructionand underground piping construction). The amount of the deterioratedasphalt in the asphalt pavement waste is typically 2 wt % to 6 wt %. Theasphalt pavement waste preferably has a penetration degree of 20 or morein consideration of ease of reclamation. It should be noted that thepenetration degree is a value determined according to JIS K2207 (1996)at 25° C.

The addition amount of the additive for reclaiming asphalt with respectto the asphalt pavement waste or the mixture of the fresh aggregate andthe asphalt pavement waste is an amount needed to restore the physicalproperties (such as penetration degree and stability) of the asphaltpavement waste to desired values, and may be appropriately determinedwithin the range of 1 wt % to 6 wt % with respect to the deterioratedasphalt in the asphalt pavement waste or the mixture of the freshaggregate and the asphalt pavement waste.

Conventionally known aggregates including natural aggregates such assize-5, 6, or 7 single-sized crushed stone, coarse sand, fine sand, andscreenings, and artificial aggregates can be used as the freshaggregate.

Next, a modified asphalt of the present invention will be described.

The modified asphalt of the present invention is obtained by adding, tostraight asphalt melted by being heated (typically heated to about 80°C. to 100° C.), a xerogel-like amorphous resin, or a gel- or dough-likeamorphous resin melted by being heated together with a waste animal orvegetable oil, and mixing the materials. While the modified asphaltdisclosed in Patent Document 3 can be blended with only up to 40 wt % ofa resin component, the modified asphalt of the present invention can beblended with up to 90 wt % of the xerogel-like amorphous resin, or thegel- or dough-like amorphous resin as a resin component. The inventor ofthe present invention has experimentally experienced the fact that auniform mixture cannot be obtained even when the straight asphalt, thewaste animal or vegetable oil, and a large amount of an amorphous resin(such as a polystyrene or a polyvinyl chloride) are stirred and mixed athigh temperature for a long time. The inventor of the present inventionfelt that this may be because the cohesive energy of the amorphous resinis so large that the uniform mixing cannot be performed, and attemptedto blend the amorphous resin in a state of reduced cohesive energy. As aresult, the inventor surprisingly found that the gel- or dough-likeamorphous resin can be blended at 70 wt % to 90 wt % intothemodifiedasphalt and that the xerogel-like amorphous resin can beblended at 1 wt % to 90 wt % into the modified asphalt.

The gel- or dough-like amorphous resin in the present invention isobtained by gradually adding, to a proper organic solvent (such as athinner, toluene, benzene, acetone, ethyl acetate, cyclohexanone,2-butanone, white kerosene, or a mixture thereof) capable of dissolvingan amorphous resin such as a polystyrene, a polyvinyl chloride, an ABSresin, or an acrylic resin, the amorphous resin at a content in therange of 100 wt % to 250 wt % to dissolve the resin, thereby bringingthe resin into a saturated state. In particular, a mixed organic solventcontaining ethyl acetate and white kerosene at a volume ratio of 0.5 to4:9.5 to 6 is preferably used for the dissolution of the polystyrene, amixed organic solvent containing cyclohexanone and white kerosene at avolume ratio of 0.5 to 4:9.5 to 6 is preferably used for the dissolutionof the polyvinyl chloride, and a mixed organic solvent containing2-butanone and white kerosene at a volume ratio of 0.5 to 4:9.5 to 6 ispreferably used for the dissolution of the ABS resin. Such gel- ordough-like amorphous resin is uniformly mixed with the straight asphaltwhen the waste animal or vegetable oil is used as a dispersant becausethe resin is in a state of reduced cohesive energy as a result of theoccurrence of a molecular shift. It should be noted that a blendingamount of the gel- or dough-like amorphous resin of less than 70 wt % isnot desirable because curing starts in a relatively short time period. Ablending amount of the gel- or dough-like amorphous resin in excess of90 wt % is also not desirable because the properties of the amorphousresin become so strong that the resin tends to solidify, which resultsin remarkably poor workability.

In addition, the xerogel-like amorphous resin in the present inventionis obtained by immersing the gel- or dough-like amorphous resin inalcohol (such as methyl alcohol, octanol, and a mixture thereof) toremove the organic solvent remaining in the gel- or dough-like amorphousresin, and drying the remainder. Such xerogel-like amorphous resin canbe uniformly mixed with the straight asphalt at a blending ratio as wideas 1 wt % to 90 wt % because the resin shows extremely highcompatibility with the straight asphalt when the waste animal orvegetable oil is used as a dispersant. It should be noted that there isno need to heat and melt the xerogel-like amorphous resin in advance atthe time of mixing.

Straight asphalt having a penetration degree of 20 to 80 is preferablyused.

The modified asphalt of the present invention can provide an asphaltpavement material excellent in mechanical properties such as stabilitybecause the blending amount of the resin component can be increased.Further, the modified asphalt whose blending amount of the xerogel-likeamorphous resin, or the gel- or dough-like amorphous resin is set to 70wt % to 90 wt % has an advantage that the modified asphalt clings tovery little production equipment such as mixers or conveying machinessuch as dump trucks. Further, when a conventional asphalt pavementmaterial is used, the asphalt pavement material cools during itstransport from an asphalt mixture factory to a construction site, withthe result that its workability is impaired. However, an asphaltpavement material to which the modified asphalt of the present inventionis added barely causes such problems because of its high heat-retainingproperty.

An asphalt pavement material of the present invention is obtained byadding the modified asphalt to a fresh aggregate, an asphalt pavementwaste, or a mixture of a fresh aggregate and asphalt pavement waste, andmelting and mixing the materials under temperatures of 155° C. to 170°C. The addition amount of the modified asphalt with respect to the freshaggregate may be appropriately determined within such a range that theamount of the modified asphalt in the asphalt pavement material to beobtained is 2 wt % to 8 wt %. In addition, the addition amount of themodified asphalt with respect to the asphalt pavement waste or themixture of the fresh aggregate and the asphalt pavement waste may beappropriately determined within the range of 1 wt % to 45 wt % withrespect to the deteriorated asphalt in the asphalt pavement waste or themixture of the fresh aggregate and the asphalt pavement waste. Theasphalt pavement material of the present invention may be furtherblended with straight asphalt as required. The melt-mixing temperatureand compaction temperature of the asphalt pavement material of thepresent invention can each be lowered by about 20° C. as compared withthat of a commercially available dense-graded asphalt mixture. Inaddition, the melt-mixing temperature and compaction temperature of theasphalt pavement material can each be lowered by about 30° C. ascompared with that of a commercially available blown asphalt mixture.Accordingly, energy consumption needed for production of the asphaltpavement material and carbon dioxide emissions can be curtailed.

The same products as those used in the additive for reclaiming asphaltcan be used as the fresh aggregate and the asphalt pavement waste in thepresent invention.

In addition, the asphalt pavement material of the present invention maybe further blended with any one of fillers such as silica, talc, calciumhydroxide, calcium carbonate, various minerals, and glass waste inaddition to the above-mentioned components. A preferred blending ratioof the filler is 35 wt % to 55 wt % with respect to the entirety of theasphalt pavement material. Since the modified asphalt of the presentinvention is blended with the amorphous resin, its bonding force withthe aggregate or the filler such as glass waste is increased and hencethe scattering of the aggregate, the glass waste, or the like toward apaved surface can be suppressed.

The additive for reclaiming asphalt of the present invention may be in asolid and in which the additive for reclaiming asphalt is taken in thexerogel-like amorphous resin obtained as described above. The solidadditive for reclaiming asphalt is obtained by heating the additive forreclaiming asphalt to 120° C. to 210° C., adding the amorphous resin tothe heated additive, mixing the materials, pouring the mixture into amold having a predetermined shape and then cooling and solidifying themixture. A preferred addition amount of the xerogel-like amorphous resinis 40 wt % to 90 wt % with respect to the solid additive for reclaimingasphalt. When the addition amount of the xerogel-like amorphous resin isless than 40 wt %, it is difficult to solidify the mixture. In addition,when the addition amount exceeds 90 wt %, it is difficult tosufficiently restore the physical properties of a deteriorated asphaltcomponent.

EXAMPLES

Hereinafter, the present invention is described in more detail by way ofExamples and Comparative Examples, but is not limited by the examples.It should be noted that a penetration degree is a value determinedaccording to JIS K2207 (1996) at 25° C.

Example 1A

A waste animal or vegetable oil (obtained from a waste disposal dealer,kinematic viscosity at 60° C.: 60 mm²/s) and a waste mineral oil(obtained from a gas station, kinematic viscosity at 60° C.: 30 mm²/s)were mixed at a ratio of 1:1 on a weight basis. It should be noted thatforeign matter was removed by passing the waste animal or vegetable oiland the waste mineral oil through a 250-mesh woven metal strainer and a440-mesh woven metal strainer before their use. After 9.1 parts byweight of straight asphalt (having a penetration degree of 20 to 40) wasadded to 90.9 parts by weight of the mixture, the resultant liquid washeated to 230° C. while the entirety of the liquid was stirred. Theliquid was held at 230° C. for 10 minutes and then left standing tocool. Thus, an additive for reclaiming asphalt of Example 1A wasobtained. Table 1 shows various physical properties of the resultantadditive for reclaiming asphalt. Table 1 also shows various physicalproperties of commercially available additives for reclaiming asphalt(FRESHSOL 200 manufactured by SHOWA SHELL SEKIYU K.K. and T-REVIVEmanufactured by Takenaka Sangyo Co., Ltd.).

TABLE 1 Quality^(*1) Example 1A FRESHSOL 200 T-REVIVE Kinematicviscosity at 40° C. 175 150.5 (mm²/s) Kinematic viscosity at 60° C. 80to 1000 80.8 526 53.39 (mm²/s) Flash point (° C.) 230 or more 240 327252 Density at 15° C. (g/cm³) 0.894 0.978 0.911 Pour point (° C.) 2 orless −27.5 −17.5 Viscosity ratio at 60° C. after 1.05 1.1 1.08 heatingof thin film Mass change ratio after heating Within ±3 −1.17 −0.07 −0.82of thin film (%) Aromatic content^(*2) (wt %) 3.4 83.5 15.6^(*1)According to “Pavement Recycling Handbook” (February 2004) ^(*2)Thearomatic content was measured by a TLC-FID method using an IATROSCAN.

As can be seen from the results of Table 1, the additive for reclaimingasphalt of Example 1A satisfies all aspects of quality as an additivefor reclaiming asphalt according to a plant recycling pavementtechnology guideline. In particular, since the additive has so low apour point, there is no need to heat the additive at the time of itstransport or storage. Further, it can be said that the additive forreclaiming asphalt of Example 1A is friendly to the environment andhumans because its aromatic content is extremely small as compared withthat of commercially available products. In addition, the additive forreclaiming asphalt of Example 1A can be available at a low cost because90 wt % or more of the additive is formed of waste.

Next, 100 parts by weight of deteriorated asphalt (asphalt extractedfrom an asphalt pavement waste, penetration degree: 27) were heated toabout 180° C. 5.6 Parts by weight of the additive for reclaiming asphaltof Example 1A were added to the deteriorated asphalt and then thematerials were mixed at about 165° C. After that, the mixture wascompacted at 147° C. to 152° C. Thus, a reclaimed asphalt test piece wasobtained. Table 2 shows various physical properties of the resultantreclaimed asphalt test piece.

TABLE 2 Example Quality^(*1) 1A Penetration degree (1/10 mm) More than60 and 80 or less 73 Softening point (° C.) 44.0 to 52.0 45 Ductility at15° C. (cm) 100 or more 113 Toluene soluble matter (%) 99.0 or more 99.9Flash point (° C.) 260 or more 317 Mass change ratio after heating 0.6or less −0.2 of thin film (%) Penetration degree residual ratio 55 ormore 78.1 after heating of thin film (%) Penetration degree ratio after110 or less 94.4 evaporation Density at 15° C. (g/cm³) 1.000 or more1.034 Kinematic viscosity at 120° C. 1130.4 (mm²/s) Kinematic viscosityat 150° C. 285.1 (mm²/s) Kinematic viscosity at 180° C. 92.5 (mm²/s)^(*1)According to “Pavement Recycling Handbook” (February 2004)

As can be seen from the results of Table 2, the asphalt reclaimed withthe additive for reclaiming asphalt of Example 1A satisfies all aspectsof quality as reclaimed asphalt. Accordingly, the additive forreclaiming asphalt of Example 1A can sufficiently restore the physicalproperties of a deteriorated asphalt component. Further, the asphaltreclaimed with the additive for reclaiming asphalt of Example 1A has akinematic viscosity at 150° C. of 285 mm²/s, which means that itsfluidity is high (when a conventional additive for reclaiming asphalt isused, the kinematic viscosity at 150° C. is 350 mm²/s or more). It isassumed from the foregoing that uniform mixing can be performed at alower temperature than a conventional one. In addition, in order thatthe kinematic viscosity of the reclaimed asphalt at 150° C. may beadjusted with the conventional additive for reclaiming asphalt to thesame level as that of Example 1A, the conventional additive needs to beadded in an amount about two to three times as large as that of Example1A. A high kinematic viscosity of the reclaimed asphalt is not desirablebecause the high kinematic viscosity leads to a reduction in strength ofa reclaimed asphalt pavement material.

Example 1B

A waste animal or vegetable oil (obtained from a waste disposal dealer,kinematic viscosity at 60° C.: 60 mm²/s) and a waste mineral oil(obtained from a gas station, kinematic viscosity at 60° C.: 30 mm²/s)were mixed at a ratio of 9:1 on a weight basis. It should be noted thatforeign matter was removed by passing the waste animal or vegetable oiland the waste mineral oil through a 250-mesh woven metal strainer and a440-mesh woven metal strainer before their use. After 9.1 parts byweight of straight asphalt (having a penetration degree of 20 to 40) wasadded to 90.9 parts by weight of the mixture, the resultant liquid washeated to 230° C. while the entirety of the liquid was stirred. Theliquid was held at 230° C. for 10 minutes and then left standing tocool. Thus, an additive for reclaiming asphalt of Example 1B wasobtained. The resultant additive for reclaiming asphalt had a density at15° C. of 0.931 g/cm³ and a flash point of 318° C.

The additive for reclaiming asphalt of Example 1B obtained in theforegoing was added at 10 wt % with respect to the deteriorated asphaltin an asphalt pavement waste (having a penetration degree of 24), andthen the materials were melted and mixed at about 180° C. Thus, areclaimed asphalt pavement material (having a penetration degree ofabout 70) was obtained.

A specimen was produced by compacting the resultant reclaimed asphaltpavement material at 165° C., and was then subjected to a wheel trackingtest (vertical load: 70 kg, 60° C. contact pressure: 6.4 kgf/cm², testtemperature: 60° C., number of times of run: 2,520, running method:chain type). As a result, the specimen had a dynamic stability (DS) of5,053 times/mm (average of three measured values) and a consolidationdeformation amount of about 1.48 mm (average of three measured values).

Comparative Example 1

A commercially available additive for reclaiming asphalt (FRESHSOL 200manufactured by SHOWA SHELL SEKIYU K.K.) was added at 18 wt % withrespect to the deteriorated asphalt in an asphalt pavement waste (havinga penetration degree of 24), and then the materials were melted andmixed at about 180° C. Thus, a reclaimed asphalt pavement material(having a penetration degree of about 70) was obtained.

A specimen was produced by compacting the resultant reclaimed asphaltpavement material at 165° C., and was then subjected to a wheel trackingtest (vertical load: 70 kg, 60° C. contact pressure: 6.4 kgf/cm², testtemperature: 60° C., number of times of run: 2,520, running method:chain type). As a result, the specimen had a dynamic stability (DS) of3,088 times/mm (average of three measured values) and a consolidationdeformation amount of about 1.71 mm (average of three measured values).

As can be seen from the results of the wheel tracking tests of Example1B and Comparative Example 1, it can be said that the reclaimed asphaltpavement material using the additive for reclaiming asphalt of Example1B has strength and heat resistance much higher than those of thereclaimed asphalt pavement material using the commercially availableadditive for reclaiming asphalt.

Example 2

A mixture containing 60 wt % of an asphalt pavement waste (having apenetration degree of 27) and 40 wt % of a fresh aggregate was heated toabout 170° C. 5.6 wt % of the same additive for reclaiming asphalt asthat used in Example 1A with respect to the deteriorated asphalt in themixture and a predetermined amount (such an amount that the totalasphalt amount was 5.0 wt %, 5.5 wt %, 6.0 wt %, 6.5 wt %, or 7.0 wt %)of fresh asphalt (having a penetration degree of 60 to 80) were added tothe mixture, and then the materials were mixed at about 170° C. Thus, areclaimed asphalt pavement material was obtained.

Table 3 shows the results of the measurement of the density, stability,flow value, percentage of voids, and degree of saturation of theresultant reclaimed asphalt pavement material. It should be noted thatthe density, the stability, the flow value, the percentage of voids, andthe degree of saturation are values determined by a Marshall testmethod.

TABLE 3 Total Flow asphalt value Percentage Degree of amount DensityStability (1/ of voids saturation (wt %) (g/cm³) (kN) 100 cm) (%) (%)Example 2 5.0 2.323 13.55 30 5.3 67.9 5.5 2.327 12.69 29 4.4 73.6 6.02.352 12.59 35 2.7 83.7 6.5 2.357 13.45 38 1.8 89.3 7.0 2.354 12.39 410.9 94.5

As can be seen from the results of Table 3, the additive for reclaimingasphalt of the present invention can produce a reclaimed asphaltpavement material whose stability and flow value are good even when itsaddition amount is as small as 5.6 wt % with respect to the deterioratedasphalt in a mixture of an asphalt pavement waste and a fresh aggregate.When an attempt was made to obtain a reclaimed asphalt pavement materialhaving the same levels of stability and flow value with a conventionaladditive for reclaiming asphalt, the conventional additive needed to beadded at 10 wt % to 14 wt %.

Example 3

1.5 Parts by weight of an expanded polystyrene were gradually added to 1part by weight of a mixed organic solvent containing ethyl acetate andwhite kerosene at a volume ratio of 2:8. Thus, the expanded polystyrenewas dissolved. Then, the materials were mixed to provide a gel-likepolystyrene. Next, the resultant gel-like polystyrene was immersed in amixed alcohol containing methyl alcohol and octanol at a volume ratio of8:2 for about 3 hours. After that, the polystyrene was taken out anddried at room temperature. Thus, a xerogel-like polystyrene wasobtained.

60 Parts by weight of the xerogel-like polystyrene and 1.5 parts byweight of a waste animal or vegetable oil (obtained from a wastedisposal dealer, kinematic viscosity at 60° C.: 60 mm²/s) were added to240 parts by weight of straight asphalt (having a penetration degree of60 to 80) melted by being heated to about 100° C., and then thematerials were mixed. Thus, a modified asphalt of Example 3 wasobtained. The resultant modified asphalt was a uniform mixture.

Example 4

A modified asphalt was obtained in the same manner as in Example 3except that the amounts of the straight asphalt and the xerogel-likepolystyrene were changed to 180 parts by weight and 120 parts by weight,respectively. The resultant modified asphalt was a substantially uniformmixture, though the modified asphalt contained a small amount of thesolidified product of the polystyrene.

Example 5

A modified asphalt was obtained in the same manner as in Example 3except that the amounts of the straight asphalt and the xerogel-likepolystyrene were changed to 120 parts by weight and 180 parts by weight,respectively. The resultant modified asphalt was a substantially uniformmixture, though the modified asphalt contained a small amount of thesolidified product of the polystyrene.

Example 6

A modified asphalt was obtained in the same manner as in Example 3except that the amount of the waste animal or vegetable oil was changedto 9 parts by weight. The resultant modified asphalt was a uniformmixture.

Example 7

A modified asphalt was obtained in the same manner as in Example 3except that the amounts of the straight asphalt, the xerogel-likepolystyrene, and the waste animal or vegetable oil were changed to 180parts by weight, 120 parts by weight, and 9 parts by weight,respectively. The resultant modified asphalt was a uniform mixture.

Example 8

A modified asphalt was obtained in the same manner as in Example 3except that the amounts of the straight asphalt, the xerogel-likepolystyrene, and the waste animal or vegetable oil were changed to 120parts by weight, 180 parts by weight, and 9 parts by weight,respectively. The resultant modified asphalt was a substantially uniformmixture, though the modified asphalt contained a small amount of thesolidified product of the polystyrene.

Example 9

A modified asphalt was obtained in the same manner as in Example 3except that the amount of the waste animal or vegetable oil was changedto 27 parts by weight. The resultant modified asphalt was a uniformmixture.

Example 10

A modified asphalt was obtained in the same manner as in Example 3except that the amounts of the straight asphalt, the xerogel-likepolystyrene, and the waste animal or vegetable oil were changed to 180parts by weight, 120 parts by weight, and 27 parts by weight,respectively. The resultant modified asphalt was a uniform mixture.

Example 11

A modified asphalt was obtained in the same manner as in Example 3except that the amounts of the straight asphalt, the xerogel-likepolystyrene, and the waste animal or vegetable oil were changed to 120parts by weight, 180 parts by weight, and 27 parts by weight,respectively. The resultant modified asphalt was a uniform mixture.

Comparative Example 2

The same operations as those of Example 3 were performed except that thewaste animal or vegetable oil was not added. As a result, the addedxerogel-like polystyrene solidified and hence a uniform mixture couldnot be obtained.

Comparative Example 3

The same operations as those of Example 3 were performed except that 1.5parts by weight of a REDICOTE E-11 (asphalt emulsifier) manufactured byLion Corporation were added instead of 1.5 parts by weight of the wasteanimal or vegetable oil. As a result, the added xerogel-like polystyrenesolidified and hence a uniform mixture could not be obtained.

Comparative Example 4

The same operations as those of Example 3 were performed except that 1.5parts by weight of DUOMEEN T (asphalt emulsifier) manufactured by LionCorporation were added instead of 1.5 parts by weight of the wasteanimal or vegetable oil. As a result, the added xerogel-like polystyrenesolidified and hence a uniform mixture could not be obtained.

Comparative Example 5

A modified asphalt was obtained in the same manner as in Example 3except that 1.5 parts by weight of Newcol 1203 (nonionic surfactant)manufactured by Nippon Nyukazai Co., Ltd. were added instead of 1.5parts by weight of the waste animal or vegetable oil. The resultantmodified asphalt was a substantially uniform mixture, though themodified asphalt contained a small amount of the solidified product ofthe polystyrene.

As can be seen from the results of Comparative Examples 3 and 4, thexerogel-like polystyrene could not be dispersed in the straight asphaltwith a commercially available asphalt emulsifier. Further, as can beseen from the results of Examples 3 to 11, and Comparative Example 2 andComparative Example 5, the waste animal or vegetable oil is assumed toserve to disperse the xerogel-like polystyrene in the straight asphalt.Although Newcol 1203 manufactured by Nippon Nyukazai Co., Ltd. candisperse the xerogel-like polystyrene in the straight asphalt, Newcol1203 is more expensive than the waste animal or vegetable oil and hencecannot be put into practical use. In addition, even when the types ofamorphous resin was changed to an ABS resin or a polyvinyl chloride, thesame tendency as that of the polystyrene was observed.

Example 12

1.5 Parts by weight of an expanded polystyrene were gradually added to 1part by weight of a mixed organic solvent containing ethyl acetate andwhite kerosene at a volume ratio of 2:8, thus dissolving the expandedpolystyrene. Then, the materials were mixed to provide a gel-likepolystyrene.

750 Parts by weight of the gel-like polystyrene and 30 parts by weightof a waste animal or vegetable oil (obtained from a waste disposaldealer, kinematic viscosity at 60° C.: 60 mm²/s) were added to 250 partsby weight of straight asphalt (having a penetration degree of 60 to 80)melted by being heated to about 100° C., and then the materials weremixed. Thus, the modified asphalt of Example 12 was obtained. Theresultant modified asphalt was a uniform mixture.

Example 13

A modified asphalt was obtained in the same manner as in Example 12except that the amounts of the straight asphalt and the gel-likepolystyrene were changed to 200 parts by weight and 800 parts by weight,respectively. The resultant modified asphalt was a uniform mixture.

Example 14

A modified asphalt was obtained in the same manner as in Example 12except that the amounts of the straight asphalt and the gel-likepolystyrene were changed to 100 parts by weight and 900 parts by weight,respectively. The resultant modified asphalt was a uniform mixture.

Comparative Example 6

The same operations as those of Example 12 were performed except thatthe waste animal or vegetable oil was not added. As a result, the addedgel-like polystyrene solidified and hence a uniform mixture could not beobtained.

Comparative Example 7

The same operations as those of Example 12 were performed except thatthe amounts of the straight asphalt and the gel-like polystyrene werechanged to 500 parts by weight and 500 parts by weight, respectively. Asa result, the added gel-like polystyrene solidified and hence a uniformmixture could not be obtained.

As can be seen from the results of Examples 12 to 14 and ComparativeExample 6, the addition of 70 wt % or more of the gel-like polystyreneenabled uniform dispersion of the gel-like polystyrene in the straightasphalt. Further, the adhesion of a large amount of the straight asphaltto a mixer was observed in Comparative Example 6 while the straightasphalt in each of the modified asphalts of Examples 12 to 14 did notcling to a mixer. On the other hand, as can be seen from the result ofComparative Example 7, when the addition amount of the gel-likepolystyrene was less than 70 wt %, the gel-like polystyrene could not bedispersed in the straight asphalt. This is assumed to be because themixed organic solvent in the gel-like polystyrene exerts a certaininfluence.

Example 15

The modified asphalt obtained in Example 13 was added at 2 wt % withrespect to the deteriorated asphalt in an asphalt pavement waste (havinga penetration degree of 27), and then the materials were melted andmixed at about 160° C., thus to obtain a reclaimed asphalt pavementmaterial.

A specimen was produced by compacting the resultant reclaimed asphaltpavement material at 150° C., and this was then subjected to a wheeltracking test (vertical load: 70 kg, 60° C. contact pressure: 6.4kgf/cm², test temperature: 70° C., number of times of run: 2,520,running method: chain type). As a result, the specimen had a dynamicstability (DS) of 15,750 times/mm and a rut depth of about 0.5 mm. FIG.1 shows the surface state of the reclaimed asphalt pavement materialafter the wheel tracking test.

Comparative Example 8

A specimen was produced from a commercially available dense-gradedasphalt mixture (modified type II) and then subjected to the wheeltracking test under the same conditions. As a result, the specimen had adynamic stability (DS) of 880 times/mm and a rut depth of about 25 mm.In addition, the wheel tracking test was performed while the testtemperature was changed to 60° C. As a result, the specimen had adynamic stability (DS) of 4,366 times/mm and a rut depth of about 5 mm.FIG. 2 shows the surface state of the asphalt pavement material afterthe wheel tracking test.

Comparative Example 9

A specimen was produced from a commercially available blown asphaltmixture and then subjected to the wheel tracking test under the sameconditions. As a result, the specimen had a dynamic stability (DS) of8,289 times/mm and a rut depth of about 1 mm. FIG. 3 shows the surfacestate of the asphalt pavement material after the wheel tracking test.

As can be seen from the results of Comparative Example 8, an asphaltpavement material obtained from a dense-graded asphalt mixture that isnow on the market had a dynamic stability (DS) of 4,366 times/mm at atest temperature of 60° C. but the dynamic stability was reduced by afactor of about 5 at a test temperature of 70° C. It can be said fromthe foregoing that ruts will immediately appear in the asphalt pavementmaterial as global warming progresses in the future, and road surfacetemperatures exceed 60° C. In contrast, it can be said that there is nofear of ruts appearing in the reclaimed asphalt pavement material ofExample 15 because the material has much higher heat resistance thanthat of the asphalt pavement material (Comparative Example 9) obtainedfrom the blown asphalt mixture that has heretofore been considered ashaving high heat resistance. In other words, it can be said that areclaimed asphalt pavement material obtained by adding the modifiedasphalt of the present invention to an asphalt pavement waste is anextremely useful alternative to the asphalt pavement material obtainedfrom a blown asphalt mixture. In addition, the melt-mixing temperatureand compaction temperature of a blown asphalt mixture needed to be setto about 190° C. and about 180° C., respectively, but the production ofthe pavement material in Example 15 was attained at temperatures about30° C. lower than those temperatures. Further, the reclaimed asphaltpavement material of Example 15 was found to have high heat-retainingproperties because the time period during which the material could becompacted after the melting and mixing was 2 hours or more.

Next, in order to investigate the mechanism via which the heatresistance of the reclaimed asphalt pavement material obtained inExample 15 improved, a specimen similar to that produced in Example 15was produced and then heated to 70° C. to 80° C. After that, thespecimen was bent and its fracture cross-section was then observed. FIG.4 is a photograph of the fracture cross-section. As can be seen fromFIG. 4, a state where a thin thread-like resin was intertwined with theentirety of the aggregate was observed.

1. An additive for reclaiming asphalt, obtained by adding straightasphalt to a mixture of a waste animal or vegetable oil and a wastemineral oil having a kinematic viscosity at 60° C. of 10 mm²/s to 40mm²/s, mixing the materials, and heating the resultant mixture to removean aromatic component.
 2. A reclaimed asphalt pavement material,comprising the additive for reclaiming asphalt according to claim 1added to an asphalt pavement waste or a mixture of a fresh aggregate andan asphalt pavement waste.
 3. A modified asphalt, obtained by adding, tomolten straight asphalt, a xerogel-like amorphous resin, which isobtained by dissolving an amorphous resin with an organic solventcapable of dissolving the amorphous resin to provide a gel- ordough-like amorphous resin in a saturated state, immersing the resin inalcohol to remove the organic solvent, and drying the remainder,together with a waste animal or vegetable oil, and mixing the materials.4. A modified asphalt, obtained by adding, to molten straight asphalt, aproduct, which is obtained by dissolving an amorphous resin with anorganic solvent capable of dissolving the amorphous resin to provide agel- or dough-like amorphous resin in a saturated state, and heating theresin to melt the resin, together with a waste animal or vegetable oil,and mixing the materials, wherein a content of the gel- or dough-likeamorphous resin in the modified asphalt is 70 wt % to 90 wt %.
 5. Anasphalt pavement material, comprising the modified asphalt according toclaim 3 added to a fresh aggregate, an asphalt pavement waste, or amixture of a fresh aggregate and an asphalt pavement waste.
 6. Anasphalt pavement material, comprising the modified asphalt according toclaim 4 added to a fresh aggregate, an asphalt pavement waste, or amixture of a fresh aggregate and an asphalt pavement waste.